﻿using System;
using System.IO;
using System.Threading;

namespace MissionPlanner.Comms
{
    public class CommsFile : CommsBase, ICommsSerial, IDisposable
    {
        // Properties
        private Stream _stream;

        private int bytecredit;
        private int currentbps;
        private DateTime lastread = DateTime.MinValue;
        private int lastsecond;
        private long length;

        private int step;

        public CommsFile()
        {
        }

        public CommsFile(string filename)
        {
            Open(filename);
        }

        public int bps { get; set; }

        // Methods
        public void Close()
        {
            BaseStream.Dispose();
        }

        public void DiscardInBuffer()
        {
        }

        public void Open()
        {
            bps = int.MaxValue;
            BaseStream = File.OpenRead(PortName);
            length = BaseStream.Length;
        }

        public int Read(byte[] buffer, int offset, int count)
        {
            if (!IsOpen)
                throw new EndOfStreamException("File not open");

            while (true)
            {
                // check if we have credit and continue
                if (count < bytecredit)
                {
                    bytecredit -= count;
                    break;
                }

                // get the time taken since last read in seconds
                var LapsedSinceLastRead = (DateTime.Now - lastread).TotalSeconds;

                // escape if we are out of range
                if (LapsedSinceLastRead < 0 || LapsedSinceLastRead > 2)
                    break;

                // get our target bps for this time slice.
                var targetbps = (int) (bps * LapsedSinceLastRead) + bytecredit;

                // check if out target+count is less than our required bps
                if (count < targetbps)
                {
                    bytecredit = targetbps - count;
                    break;
                }

                Thread.Sleep(1);
            }

            lastread = DateTime.Now;

            if (lastsecond != DateTime.Now.Second)
            {
                //Console.WriteLine("CommsFile Read bps {0}", currentbps);
                currentbps = 0;
                lastsecond = DateTime.Now.Second;
            }

            currentbps += count;
            var ret = BaseStream.Read(buffer, offset, count);

            if (buffer[0] == 254 && offset == 1)
                step = buffer[1] + 5 + 2; // + header + checksum

            step -= ret;

            // read the timestamp
            //if (step == 0)
            //BaseStream.Read(new byte[8], 0, 8);

            return ret;
        }

        //int Read(char[] buffer, int offset, int count);
        public int ReadByte()
        {
            return BaseStream.ReadByte();
        }

        public int ReadChar()
        {
            return BaseStream.ReadByte();
        }

        public string ReadExisting()
        {
            return "";
        }

        public string ReadLine()
        {
            return "";
        }

        //string ReadTo(string value);
        public void Write(string text)
        {
        }

        public void Write(byte[] buffer, int offset, int count)
        {
        }

        //void Write(char[] buffer, int offset, int count);
        public void WriteLine(string text)
        {
        }

        public void toggleDTR()
        {
        }

        public void Dispose()
        {
            try
            {
                if (BaseStream != null)
                    Close();
            }
            catch
            {
            }
        }

        public Stream BaseStream
        {
            get => _stream;
            set
            {
                _stream = value;
                length = _stream.Length;
            }
        }

        public int BaudRate { get; set; }

        public int BytesToRead
        {
            get
            {
                if (!BaseStream.CanRead) return 0;
                return (int) (BaseStream.Length - BaseStream.Position);
            }
        }

        public int BytesToWrite { get; set; }
        public int DataBits { get; set; }
        public bool DtrEnable { get; set; }

        public bool IsOpen
        {
            get
            {
                if (BaseStream != null && BaseStream.CanRead) return BaseStream.Position < length;
                return false;
            }
        }

        public string PortName { get; set; }
        public int ReadBufferSize { get; set; }
        public int ReadTimeout { get; set; }
        public bool RtsEnable { get; set; }

        public int WriteBufferSize { get; set; }
        public int WriteTimeout { get; set; }

        //void DiscardOutBuffer();
        public void Open(string filename)
        {
            bps = int.MaxValue;
            PortName = filename;
            BaseStream = File.OpenRead(PortName);
            length = BaseStream.Length;
        }

        public void SetLength(long length)
        {
            this.length = length;
        }
    }
}